1. Field of the Invention
The present invention relates to a circuit device and a method of manufacturing the circuit device. In particular the present invention relates to a circuit device in which encapsulating resin coats a circuit board having a circuit element mounted thereon, and a method of manufacturing the circuit device.
2. Description of the Related Art
FIG. 8 shows a hybrid integrated circuit device 100 of the related art having a structure in which an electric circuit mounted on the surface of a board 101 (see Japanese Patent Application Publication No. Hei 11-340257). A conductive pattern 103 is formed on the surface of the rectangular board 101 with an insulating layer 102 formed in between. A circuit element 105 is fixed at a predetermined position on the conductive pattern 103, and thereby a predetermined electric circuit is formed. In this example, a semiconductor element and a chip element are connected, as circuit elements, to the conductive pattern 103. A lead 104 is connected to a pad 109 that is a portion of the conductive pattern 103 formed in a peripheral area of the board 101. The lead 104 functions as an external terminal. Encapsulating resin 108 has a function of encapsulating the electric circuit formed on the surface of the board 101.
The method of manufacturing the hybrid integrated circuit device 100 can be summarized as follows. Firstly, a hybrid integrated circuit including the conductive pattern 103 and the circuit element 105 is mounted on the top surface of the board 101. Then, the lead 104 is fixed, with a solder, to the pad 109 located in a peripheral area of the board 101. Then, the encapsulating resin 108 is formed to cover the board 101 and the lead 104. The encapsulating resin 108 is usually formed by transfer molding using a mold. For the transfer molding, a mold with an internal-wall shape corresponding to the external shape of the encapsulating resin 108 is firstly prepared, and the board 101 is placed in the cavity of the mold. Then, encapsulating resin in the form of a liquid is injected into the cavity, and thereby the top surface, the side surfaces, and the bottom surface of the board 101 are coated with the encapsulating resin. Then, the encapsulating resin in the cavity is cured by heating. Then, the hybrid integrated circuit device 100 encapsulated by the encapsulating resin 108 is taken out of the mold.